The present invention relates to a percutaneous catheter based method and apparatus for plugging a Patent Foramen Ovale formed in the heart of a human.
The human cardio-pulmonary system, for oxygenating and circulating blood throughout the body, is dramatically different between normal adults and fetuses. In the adult circulatory system, blood is pumped from various parts of the body to the right side of the heart, and then through the pulmonary artery to the lungs. Following oxygenation at the lungs, the blood travels through the pulmonary veins to the left side of the heart, and is pumped from there through the aorta to the brain and other parts of the body.
During gestation, human fetuses do not breathe air. Rather, their blood is oxygenated by maternal blood through the placenta. Hence, not only is there no great need to divert all blood to the lungs upon every trip through the circulatory system, but additionally the fact that the lungs are collapsed makes it difficult for blood to flow and significantly raises the pressure in the pulmonary path of the circulatory system. To bypass the unnecessary trip to the lungs, blood in the fetal heart is shunted directly from the right chamber into the left chamber of the fetal heart through a valve-like opening in the wall separating the two sides of the heart, known as the Foramen Ovale. The blood is then pumped from the left side of the heart into the aorta and directly to the brain and other points in the fetal body.
After birth, the cardio-pulmonary system changes significantly. The lungs fill with air, reducing the resistance to blood flow through the lungs, and thus dramatically decreasing the pressure of the pulmonary path, i.e., the pulmonary artery and the right side of the heart. In this condition, the left side of the heart is maintained at a somewhat higher pressure than the right side, and the valve-like Foramen Ovale is forced closed, sealing off blood flow between the two sides of the heart. Eventually, fibrous tissue covers the closed Foramen Ovale and permanently seals it off. However, in twenty-five percent to thirty-five percent of adults, the Foramen Ovale remains open, or xe2x80x9cpatent.xe2x80x9d This allows un-oxygenated blood to flow directly from the right side of the heart into the left side, where it is carried through the aorta directly to the brain and other parts of the body. This shunting of the blood directly from the right to the left side of the adult heart, thus by-passing its trip to the lungs, can occur whenever the pressure in the right side of the heart exceeds that in the left. This condition occurs upon heavy lifting or at other times of great physical exertion, or during a Valsalva maneuver (an abdominal constriction performed while holding one""s breath).
Not only does the mixing of un-oxygenated blood with oxygenated blood dramatically reduce the efficiency of the cardiopulmonary system, it is believed to contribute to life-threatening ischemic strokes through paradoxical embolism. When blood clots in veins break off, or embolize, they normally travel through the right side of the heart and to the lungs, which act as a filter. The clots are thus normally filtered from the arteries, in particular the aorta and carotid arteries leading to the brain. In a paradoxical embolism, clots pass from a vein into an artery, such as through a Patent Foramen Ovale (PFO) or other atrial septal defect. If carried to the brain, the clots can obstruct the arterial blood supply, leading to an ischemic stroke. Once detected, the PFO condition requires either a regimen of anti-coagulants to prevent further clots, or closing of the PFO.
The traditional method of closing a PFO is open-heart surgery. This is expensive, complex, involves significant risk due to general anesthesia, infections, etc., and requires an extensive and painful recovery period. Catheter-based methods of closing a PFO are known in the art. Typically, these catheter-based solutions comprise a collapsed, expandable, or inflatable sealing element. The element is transferred through the catheter in a collapsed state, and is expanded upon deployment at the PFO within the heart. Such prior art devices typically deploy an expandable element on either side of the PFO, i.e., with a portion in both the left and right sides of the heart. Once deployed, the element is detached from the catheter and the catheter is withdrawn, leaving the element permanently in place. These prior art systems are deficient in that they depend on proper mechanical deployment of an element from a collapsed to an expanded state once positioned within the heart. If the element does not deploy, or deploys in an incorrect manner, it must be recompressed and withdrawn. Also, once inserted, the element is difficult or impossible to remove, since it has expanded on both sides of the PFO and cannot be removed.
The present invention entails a method of plugging or sealing a Patent Foramen Ovale (PFO) formed in the heart. The method entails inserting a threaded plug into the PFO and rotating the threaded plug and securing the threaded plug in the PFO.
As embodied in one particular surgical procedure, the method further entails directing a guide wire into the heart and the PFO, and inserting a catheter over the guide wire and extending the catheter towards the PFO. Thereafter the threaded plug is secured to a carrier and the guide wire is threaded through both the carrier and the threaded plug. Thereafter, the carrier and threaded plug are moved towards the PFO. After the threaded plug has been secured within the PFO, the threaded plug is decoupled from the carrier. In one particular methodology of carrying out the above surgical procedure, a first member or flexible connector is secured to the threaded plug and both the carrier and the first member remain connected or secured to the threaded plug as it is advanced towards the PFO. In this particular embodiment of the invention, the first member or flexible connector is disconnected from the threaded plug first. Thereafter, the threaded plug is urged from the carrier.
In addition, the present invention entails a surgical kit for plugging or sealing an opening in the heart. The surgical kit includes a threaded plug adapted to be secured into the opening of the heart. Further, the surgical kit includes a carrier for holding the threaded plug and for delivering the threaded plug to the opening in the heart. Finally, the surgical kit includes a catheter for receiving the carrier and the threaded plug and permitting the carrier and the threaded plug to be moved through the catheter to the opening in the heart.
Finally, another aspect of the present invention entails a threaded plug for plugging an opening in the heart. The threaded plug basically comprises a tip and a circumferential lip spaced from the tip and adapted to lie adjacent the heart tissue surrounding the opening in the heart. There is provided a threaded portion disposed generally between the tip and the circumferential lip that includes a surrounding thread pattern formed on the outer surface of the threaded plug. The opening in the heart is plugged or sealed by rotating or screwing the threaded plug into the opening.